Display panels, such as those used in personal computers, digital assistants, and mobile (“cell”) telephones, often use a backlight in combination with a diffuser panel to illuminate a liquid-crystal display (“LCD”) panel. The backlight provides white light that is controlled by the LCD panel to produce a color display. Cold-cathode fluorescent lamps (“CCFLs”) are frequently as backlights in display panels.
A CCFL is typically a tube filled with gas or vapor and coated on the inside with phosphors. A current is passed through the tube, causing the gas or vapor to emit light that is converted to other wavelengths by the phosphors to produce white light. The CCFL is typically driven by a sinusoidal signal, and the brightness is regulated by controlling the current through the tube. It is generally desirable to maintain the CCFL in an ON condition during use.
Visible light communication (“VLC”) is used to transmit data from one electronic device to another. Some systems use an auxiliary light-emitting diode (“LED”) lamp controlled by a transmitting computer, such as notebook or laptop computer, to illuminate an optical receiver of a receiving computer. However, this is cumbersome and consumes additional power, which is often limited in a portable electronic device such as a notebook or laptop computer.
Therefore, VLC techniques that avoid the problems of the prior art are desirable.